We are seeking funds to replace 16 year old Jasco J-500 circular dichroism (CD) spectrometer, currently the only CD instrument at the University of Florida. The proposed instrument will be state-of-the-art and will include a stopped flow accessory, an automated titration accessory, fluorescence detection capabilities, and a thermoelectric device for controlling sample temperature. Thirteen investigators (including seven NIH-funded projects) from three colleges and seven departments in the University of Florida have contributed research justifications for this very important and very basic instrumentation. The proposed instrument will be part of a new structural biology, biophysical instrumentation (SBBI) facility and will complement existing NMR, x- ray crystallography, optical microscopy, and computational facilities. These facilities and seven faculty research groups form the core of an expanding structural biology program at the University of Florida, and the proposed CD spectrometer will be a viral component for NIH-funded research efforts, other federally funded research efforts, and graduate education in structural biology. The CD spectrometer will be located in the McKnight Brain Institute of the University of Florida (MBI-UF) because MBI-UF is the focal point for structural biology groups and instrument at UF. As part of the institutional support, MBI-UF will provide space, technical, and computer support for the instrument for 3 years., The University of Florida will additionally provide maintenance costs and service contrasts for 3 years, making the instrument free and readily available for all UF researchers, in the following priorities: contributors to this proposal (75%), other NIH-funded projects, other projects, and graduate or undergraduate education.